Chain door lock



March 24, 1964 J FRIEDMAN 3,125,875

CHAIN DOOR LOCK Filed Sept. 25. 1961 INVENTOR. GEORGE J. FRIEDMAN ATTORNEY United States Patent O 3,125,875 CHAIN DOOR LOCK George J. Friedman, Brooklyn, N.Y., assignor, by mesne assignments, to Iris Friedman, New York, N.Y. Filed Sept. 25, 1961, Ser. No. 140,359 5 Claims. (Cl. 70-93) This invention relates to lock mechanisms and in particular to chain door locks.

In the past, chain door locks have consisted of two plate members, one of which had defined therein an elongated slot into and along which a slide element was adapted to be inserted and removed. The slide element was unremovably connected by a chain to the second plate member. The slide plate and the second or mounting plate each were adapted to be secured on different surfaces of a doorway. Thus, for example, it was common to place the slide plate member on the door jamb while the mounting plate member, to which the chain and slide element was unremovably secured, was generally mounted on the door, although the mounting location of the plate members could be reversed. The described construction had long been wanting in the ability of operating the chain door lock in such manner that the same could be released from outside the doorway as well as from inside the doorway without, however, removing the slide element from engagement with the elongated slot in the slide plate.

Accordingly, the desideratum of the invention is to provide a chain door lock that enables the same to be 7 3,125,875 Patented Mar. 24, 1964 while the plate member 14 is secured by screws 20 to the door 22. It should be readily recognized by those skilled in the art that this relative arrangement of securement is one of a matter of choice and may be reversed without in any way affecting the operation of the chain door lock 10.

The plate member 12 is generally referred to as a slide plate because it has an elongated slot 24 defined therein with one end of the slot terminating in an enlarged opening 26. A slide element 28 having a circular head 30 of slightly smaller diameter than that of the opening 26 is adapted to pass through the opening so that a narrower diameter annular wall (not shown) will engage with the defining walls of the slot 24. The slide element 28 is connected to the endmost link of a chain 32 while the opposite end of the chain is connected with a latch bolt generally identified by the numeral 34.

The latch bolt 34 is provided at its rear with a finger knob 36 by which the same may be manually manipulated. The body portion 38 of the latch bolt 34 defines a smooth circular guide surface that terminates at its rear in a stop shoulder 40 and has a stem 42 that extends forkey operated from either one side or" the doorway or the other with equal ease and facility.

Another object of the invention is to provide a chain door lock in which the latch bolt is automatically ejected from its latched position when its latching engagement is released without requiring the necessary operation and removal of the slide element from the slot in the slide plate.

Still another object of the invention resides in the novel and unique features and details of construction that facilitate the automatic latching action of the lock mechanism when the latch bolt is inserted thereinto.

Still another object of the invention is to provide a lock mechanism of simple, inexpensive construction that requires no special mechanical aptitude to operate, that is easily installed and safe in use, and one that can be used with equal facility in connection with chain door locks as Well as for purposes of general application.

Other and further objects of this invention reside in the structures and arrangements hereinafter more fully described with reference to the accompanying drawing in which:

FIG. 1 is a perspective view of a chain door lock constructed according to the teaching of the invention,

FIG. 2 is a partial cross section of FIG. 1 taken in the direction of line 22 and illustrating the same in its engaged or latched condition,

FIG. 3 is a view similar to FIG. 2 illustrating the lock mechanism thereof in its unlatched condition,

FIG. 4 is a cross section of FIG. 2 taken along line 4-4,

FIG. 5 is a cross section of FIG. 4 taken along line 5-5, and

FIG. 6 is a view similar to FIG. 5 illustrating the lock mechanism in its unlatched condition.

Referring to the drawing, the chain door lock thereshown is generally identified by the numeral 10. The lock 10 comprises two plate members 12 and 14 each of which is adapted to be mounted on different parts of a doorway. In FIG. 1 of the drawing, the plate member 12 is shown secured by screws 16 to the door jamb 18 ward thereof. The stem 42 is formed integral with a displacement head 44 of substantially the same diameter as the body portion 38. The head 44 is conically shaped at 46 tapering toward its forward end.

Plate member 14 is formed with an enlarged body that may be described as a housing 48 in which a blind hole or aperture 59 is defined. The aperture 50 extends into the housing 48 from the face thereof and is of such diameter as to smoothly receive and permit guided movement of the head 44 and body portion 38 therein and for movement therealong. Positioned within and at the blind end of the aperture 50 is an ejection means in the form of a conical spring 52.

Also defined within the housing 48 is a hole 54, the longitudinal axis of which is directed at an angle transverse to and for communication with the latch bolt receiving aperture 50. Positioned within the hole 54 is a keeper element 56 the lower end of which is normally engaged with and constantly biased upward toward the aperture 50 by a spring 58 that is seated within a suitable hole (not numbered) provided therein at the lower end thereof. The opposite or lowermost end of the spring 58 abuts a plug 60 that is press fit into the hole 54 to close the same. The upper end 62 of the keeper element 56 is joined with the lower end for conjoint movement by a connecting narrowed stem 64. Consequently, the keeper element 56 is normally urged upward by the spring 58 so that its upper end or engaging head 62 extends well into the aperture 50 and thus normally in the path of obstructing movement of the latch bolt 34.

The operation of the keeper 56 is controlled by an actuator in the form of a key operated tumbler 66. The tumbler 66 may be of any well known construction, of which the interior details do not form any part of the invention. However, for purposes of explanation, the body of the tumbler rotates smoothly in a hole 68 provided in the housing 48, the longitudinal axis of which is directed at an angle transverse to and in communication with the hole 54 in which the keeper element 56 moves. The tumbler pins 79 extend radially into engagement with a radially directed longitudinally extending slot 72 that extends the length of the tumbler hole 68. When the proper key 74 is inserted into the keyway of the tumbler 66, the tumbler pins 70 retract radially inward into the body of the tumbler and out of engagement with the slot 72, thereby permitting the tumbler to be rotated by rotation of the key. Removal of the key from the tumbler permits the pins '70 to extend radially outward for renewed engagement with the slot 72. When the pins are so engaged with the slot, the tumbler 66 is incapable of rotation.

Eccentrically mounted on the forward face of the tumbler 66 is an actuator finger 76. When the tumbler is rotated, the-finger 76 is also rotated. The rotation of the tumbler and its actuator finger is limited by a plurality of arcuately spaced stop surfaces '78 and 86 provided on an enlarged diameter shoulder 82 at the front of the tumbler 66. A similarly sized enlarged diameter opening is provided in the housing 43 to accommodate the shoulder 82. However, projecting lengthwise of the enlarged opening is a set of arcuately spaced projections 84 and 86. The relative arcuate spacing between the projections 84 and 86 is less than that of the stop surfaces 7 8 and 80 on the shoulder 82 of the tumbler.

Hence, when the tumbler is rotated by the key 74 after the same has retracted the tumbler pins 7 6 radially inward and out of engagement with the slot 72, the degree of rotation is limited by the engagement of one of its surfaces 78 or 80 with a respective one of the projections 86 or 84. Thus, when the key 74 is upright as shown in FIGS. 1, 2, 4 and 5, the stop surface 86 engages with the projection 84 on the housing. When the key and tumbler are rotated to their actuating position, the stop surface 80 thereof rotates away from abutment with the projection 84 until the stop surface 78 abuts the projection 86 and thereby limits the rotation of the tumbler 66 within the housing 48.

It will be recognized by those skilled in the art that the eccentrically mounted actuator finger 76 moves with the rotation of the tumbler 66 as a result of the manual manipulation of the key 74. Thus, when the key '74 or the keyway of the tumbler 66 is upright as shown in FIGS. 1, 2, 4 and 5, the tumbler is in its inactive position and the actuator finger 76 is similarly positioned. However, the shoulder at the lower end of the stem 64- of the keeper element 56 is urged into abutment with the actuating finger 76 by the operation of the resilient yieldable spring 58. The inactive position of the actuator finger and the remaining actuator tumbler thus permits the keeper ele ment 56 to extend upward into the aperture 59 partially obstructing the same. On the other hand, when the tumbler 66 is rotated to its active or actuating position by the manipulation of the key 74 therein, the finger 76 moves against the abutting shoulder of the keeper element in opposition to the spring 58 to withdraw or retract the keeper element from its position within the aperture 50.

In operation, when the door 22 is closed, one may apply the slide element 28 to engage with the plate member 12 as shown in FIG. 1 and also secure the latch bolt 34 in the housing 48. This may be accomplished simply by inserting the conically shaped head 46 of the latch bolt into the aperture 50. As the conically shaped head 46 moves into engagement with the partially obstructing head 62 of the keeper element 56, the keeper element is forced downward against the opposing force of the spring 53 and out of surface abutment with the actuator finger 76. During this relative movement, the keeper rides along the head 46 until the head is inserted into the aperture 50 and into the confines of the narrowed facing opening of the conical spring 52 as shown in FIG. 5.

The head 44 and body portion 38 of the latch bolt 34 guide the movement of the latch bolt into the aperture 50 until such time as a compression is placed upon the spring 52 within the aperture and the head 44 of the latch bolt 34 has passed completely beyond the head 66 of the keeper element 56. When this occurs, the keeper element immediately springs back upward against the stem 42 of the latch bolt and behind the head 44. The rear surface of the head 44 and the circular upper end 62 of the keeper 56 function as engaging means that automatically cooperatively engage with each other to retain the latch bolt in its latched position within the aperture 56 compressing the spring 52 therein. Thereafter, the ejection spring 52 applies a force against the head 44 of the latch bolt that normally tends to move the same outward of the aperture 50 and serves to retain the same in cooperative engagement with the keeper 56.

With the chain door lock 10 thus engaged as shown in FIG. 1, the door 22 may be partially opened to provide the person on the inside of the door to see out therefrom. The chain door lock 10 may be released from the inside simply by again closing the door 22 and moving the slide element 28 along the elongated slot of the plate member 12 and outward from engagement therewith at the enlarged opening 26. However, one may open or release the chain door lock 10 from the outside even when the door 22 is partially open. This may be accomplished by reaching through the partially opened door and inserting the key 74 into the tumbler 66.

Insertion of the key retracts the pins 76 radially from engagement with the slot 72 thereby releasing the tumbler for rotation. As the tumbler is rotated from its position shown in FIGS. 1, 2, 4 and 5 to its position shown in FIGS. 3 and 6, the actuator finger 76 rotates with it. All during its rotation it bears against the adjacent abutting surface of the keeper element 56 to depress the keeper element in opposition to the spring 58 and withdraw the head 62 thereof out of cooperative engagement with the engaging rear surface of the head 44 of the latch bolt 34. As previously described, the rotation of the tumbler 66 is limited by its stop surface 73 engaging the projection 86 on the housing. However, immediately upon the retraction of the head 62 from obstructing abutment with the engaging surface of the head 44 of the latch bolt, the latch bolt is now free to move in a direction outward of the aperture 56. This outward movement of the latch bolt 34 is enhanced and in fact fully effected by the immediate expansion of the ejection spring 52. In practice, the ejection spring 52 actually shoots or throws the latch bolt smoothly out of the aperture 56 to completely dispossess the same and disconnect the latch bolt from engagement with the plate member 1'4. The chain door lock 10 is now released and the door 22 may be opened from the outside.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation maybe made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

I claim:

1. In a chain door lock having a slide plate, a slot in said slide plate, a slide movable into and out of said slot for engagement with and disengagement from said slide plate, a chain connected at its one end with said slide; a lock mechanism comprising a housing having a first hole with a blind end defined therein, a latch bolt connected with said slide at the other end of said chain and movable into and out of said first hole, a movable keeper in a second hole in said housing transverse to said first hole, spring means normally moving said keeper toward engagement with said latch bolt when said latch bolt is in said first hole, means cooperable with said keeper to move said keeper out of engagement with said latch bolt, and spring means wholly within said first hole to eject said latch bolt from said first hole when said keeper is moved out of engagement therewith.

2. The chain door lock as defined in claim 1 in which the said means normally moving said keeper toward engagement with said latch bolt comprises spring means wholly within the said second hole, and the said means to move the said keeper out of engagement with the said latch bolt comprises a reduced portion on the said keeper and locking means having actuator finger means adapted to engage the reduced portion of the said keeper.

3. The chain door lock as defined in claim 2 in which the said locking means comprises a tumbler lock operated by a separable key.

4. A chain door lock comprising chain means adapted to be fastened to the inside of a door and a door frame of a structure, or a portion thereof, by fastening means to permit restricted opening of the said door, in which at least one of the said fastening means comprises a housing having first mentioned hole means within the said housing having a longitudinal axis perpendicular to the said door and frame therefor adapted to receive a latch bolt having a longitudinal axis substantially concentric to the said longitudinal axis of the first mentioned hole means, said latch bolt comprising a tapered forward end, an opposite end with finger gripping means, means adapted to hold a portion of the said chain means positioned between the said forward end and the said finger gripping means, and a reduced portion between the said chain holding means and the said tapered forward end; said housing comprising a second hole means having a longitudinal axis substantially perpendicular to the axis of the said first mentioned hole means adapted to hold a movable keeper having a longitudinal axis substantially concentric to said longitudinal axis of the said second mentioned hole means, said keeper comprising a first end, a second end and a reduced portion between the said first and second ends; a third hole means Within the housing having a longitudinal axis substantially perpendicular to a plane containing the longitudinal axes of said first and second hole means and adapted to hold a rotatable locking means, said second mentioned hole means within the housing having biasing means contained therein adapted to act against a portion of the said housing and the said second end of the said keeper and to urge the said first end of the said keeper into the recessed portion of the said latch bolt when it is in position in the said first mentioned hole means in the said housing, and said locking means having actuating finger means at one end thereof, a portion of which is positioned within the area defined by the said recessed portion of the said keeper means and the said second mentioned hole means, said locking means adapted to move the said finger actuating means from a first unbiased position to a second position bearing against the said recessed portion of the said keeper and against the bias of the said biasing means, and to move the moveable keeper from a normal locking position to an unlocking position.

5. The chain door lock defined in claim 4 in which the said locking means comprises a tumbler lock operated by a separable key.

References Cited in the file of this patent UNITED STATES PATENTS 795,882 Atkin Aug. 1, 1905 807,779 Rinald Dec. 19, 1905 832,420 Rinaldy Oct. 2, 1906 2,966,053 Mintz Dec. 27, 1960 FOREIGN PATENTS 6,448 Great Britain Mar. 15, 1912 302,661 Germany Dec. 20, 1917 

1. IN A CHAIN FOR DOOR LOCK HAVING A SLIDE PLATE, A SLOT IN SAID SLIDE PLATE, A SLIDE MOVABLE INTO AND OUT OF SAID SLOT FOR ENGAGEMENT WITH AND DISENGAGEMENT FROM SAID SLIDE PLATE, A CHAIN CONNECTED AT ITS ONE END WITH SAID SLIDE; A LOCK MECHANISM COMPRISING A HOUSING HAVING A FIRST HOLE WITH A BLIND END DEFINED THEREIN, A LATCH BOLT CONNECTED WITH SAID SLIDE AT THE OTHER END OF SAID CHAIN AND MOVABLE INTO AND OUT OF SAID FIRST HOLE, A MOVABLE KEEPER IN A SECOND HOLE IN SAID HOUSING TRANSVERSE TO SAID FIRST HOLE, SPRING 